CS9201

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4

CIRCUIT DESCRIPTION

VOLTAGE REFERENCE AND OUTPUT

CIRCUITRY

Output Stage Protection

The output stage is protected against overvoltage, short

circuit and thermal runaway conditions (Figure 8).

If the input voltage rises above 32 V (typ), the output shuts

down. This response protects the internal circuitry and

enables the IC to survive unexpected voltage transients.

Should the junction temperature of the power device

exceed 180

°C (typ) the power transistor is turned off.

Thermal shutdown is an effective means to prevent die

overheating since the power transistor is the principle heat

source in the IC.

Figure 8. Typical Circuit Waveforms for Output

Stage Protection

Load

Dump

Short

Circuit

Thermal

Shutdown

> 32 V

GND

CS9201

0.1

µF

* C1 is required if regulator is distant from power source filter.

Figure 9. Application and Test Diagram

APPLICATION NOTES

STABILITY CONSIDERATIONS / NOCAP

Normally a low dropout or quasi–low dropout regulator

(or any type requiring a slow lateral PNP in the control loop)

necessitates a large external compensation capacitor at the

output of the IC. The external capacitor is also used to curtail

overshoot, determine startup delay time and load transient

response.

Traditional LDO regulators typically have low unity gain

bandwidth, display overshoot and poor ripple rejection.

Compensation is also an issue and depends on the external

capacitor value, ESR (Equivalent Series Resistance) and

board layout parasitics that all can create oscillations if not

properly accounted for.

NOCAP is an ON Semiconductor exclusive output stage

which internally compensates the LDO regulator over

temperature, load and line variations without the need for an

expensive external capacitor

NOCAP is ideally suited for slow switching or steady

loads. If the load is characterized by transient current events,

an output storage capacitor may be needed. If this is the case,

the capacitor should be no larger than 100 nF. With loads

that require greater transient suppression, a regulator with a

traditional output stage (such as the CS8221) may be better

suited for proper operation.